Orionids, Taurids and Leonids... Oh My!

Thanks Russ. My observing site is my front yard in New Mexico, and was chosen in part for being a nice dry and dark site (though not as dark as I'd initially hoped).

The time lapse method captures ~95% of all the starlight in one night. I've stacked the odds in my favor and it would be unusual if I didn't get any meteors. I set my intervalometers to 27 seconds and take continuous 25 second exposures, with the two seconds at the end for writing to flash. In any given hour I capture 56 minutes of starlight.

I haven't yet archived the stills from the shoot where I caught the long, low, green Leonid I posted above. I put a camera out at 6:30pm that night and took it down around 7:00am the next morning after 1,880 photos. So in that 12.5 hours I caught more than 11.5 hours of starlight (I accelerate the intervalometer at sunset and sunrise which skews my calculations a little).

I've heard people worrying about wear on the shutter. By my calculations I've taken a quarter million photos with each camera since February of this year. Maybe I've almost worn them out, but I'm not going to slow down now. This is too much fun, and worth wearing out cameras for.

Mike

P.S. I turn off long exposure noise reduction, since that would halve the amount of time I could record.

RustierOne wrote:

Thanks Mike for he info - all very interesting. What intervalometer do you use?

I've got two GentleLED-Auto and have been pretty happy with them. I looked at the TEMPUS too and it looks a little easier to use for a little more money. The main downside to the Gentle is if I forget my little screwdriver when I'm in the field (and I've done it once now) I'm really hurting to change the interval.

Mike

Very nice!  I love capturing meteors.  The bottom two may actually be flaring satellites.  Sometimes it is very hard to tell the difference.

Wade

t_wade wrote:

Very nice! I love capturing meteors. The bottom two may actually be flaring satellites. Sometimes it is very hard to tell the difference.

You're right, it is hard to tell the difference and when I was showing my time lapses after Thanksgiving dinner last night one viewer commented "oh the shooting stars!". I explained that what she was seeing were airplanes and satellites because it is virtually impossible to spot meteors in the time lapses when they are just 1 of 24 frames per second (unless there's an ion train which is one reason why they are exciting).

I've seen a time lapse recently where the video was slowed down to emphasize a meteor that was just a single still that they faded in and out in order to really emphasize it. I suppose I could do something like that too for the people who want to see meteors in my time lapses, but it is a lot more work than my current compilation process.

So knowing the likelihood for confusion I do a careful frame by frame analysis of my stills and use these criteria to help me determine what I'm looking at.

1) The satellites and airplanes typically appear in 3-4 frames depending on the direction they're traveling relative to my camera. Anything that only appears in a single frame is usually a meteor, unless it is close to sunrise. I've observed that as the sun is just rising I can often see numerous satellites in every frame and they are often flaring and only appearing in 1-2 frames.

2) The meteors almost always have tapered trails where the planes and satellites are blockier on the ends, unless it is close to dawn. The meteors often have more green in their trails too, but neither of these is a sufficient diagnostic by itself and I generally can't tell from just one single photo what I'm looking at.

3) Persistent ion trains provide a dead giveaway of meteors, as with the one entitled "Leonid at the Crack of Dawn". The bulge in the middle of that meteor is the ion train beginning to deform. It was visible in several subsequent frames until sunrise washed it out. The only danger in using an ion train is an airplane contrail false positive, but criteria #1 almost always applies to airplanes in a clear sky (I'm having an email discussion about contrails with a relative who believes in chemtrails, and have been educating myself over the years about contrails with help from a friend who is an atmospheric physicist and who has consulted with a major manufacturer on the problem of contrail cirrus over Europe).

This process got me thinking a bit recently... I have stills with multiple planes and satellites in the sky, sometimes crossing each other's trails. Those photographs look at lot more impressive when you don't know what you're looking at. So what makes the genuine meteor photos so special then? They're just little streaks of light and not all that visually impressive. It is more what they are than how they look, which is why I try to be very careful with my identifications.

Mike

I ran across this site linked on Space.com for a Leonid photo, and while looking around encountered this unbelievable photo and account of the Mason Dixon Meteor. The process he went through identifying his meteor photo really puts my process to shame.

I went back and cropped a few frames to show the ion train for the Leonid at the Crack of Dawn. I also tried the invert and posterize tricks mentioned in the Mason Dixon Meteor blog. Posterize was of no use at all in viewing the ion train in subsequent frames, but I think it becomes a little more visible when inverted. Here's 1:1 crops. It is visible in about 4-5 more frames but gets more distended and washed out. When I put it together in video and slow it down and compress it for upload, it's pretty much gone.

Meteor and ion train in same shot

Ion train deforming in shot #2

Ion train in shot #3

The way that the ion trains dissipate is fairly different from the way that contrails dissipate owing to the very high altitudes the ion trains are normally created at compared to contrails. There's usually an S shape that results from the ion trains. I have to concede that an airplane passing through a tiny pocket of humid air could create a similar brief contrail that could deform in the same way.

I wanted to also add to my last post that I do see satellite flares at non-dawn times, but they always seem to take 3-5 frames to start and disappear at that time of night. I call them flares because I don't see their transit from edge to edge of my sensor and imagine it is moving in and out of the earth's shadow that causes it.

I stand corrected.  The ion trail is a dead giveaway.  The Leonid meteor is a fantastic catch.  Your procedure in determining if something is a meteor or not is about what I go through too.  I'll read the link you posted later.

Wade